module shape ( L, H, W, D) {
polyhedron(
    points = [

      	     [  W/2,  0 , 0], 
      	     [  W/2,  0 , H], 
             [ -W/2,  0 , H],
             [ -W/2,  0 , 0],

      	     [  W/2,  L , 0], 
      	     [  W/2,  L , H], 
             [ -W/2,  L , H],
             [ -W/2,  L , 0],

	     [  W/2 -D ,  0 , H + D],
	     [ -W/2 +D ,  0 , H + D] , 	     
	     [ -W/2 +D ,  L , H + D],
	     [  W/2 -D ,  L , H + D], 	     	     
	     ],

      faces  = [
      	     [ 0, 1,   8, 9, 2, 3],
	     [ 4, 7,   6, 10, 11,5],
	     [ 0,  4, 5, 1],
	     [ 0,  3, 7, 4],
             [ 3,  2, 6, 7],
             [ 8,  11, 10, 9],
	     [ 1,  5, 11,8 ],
	     [ 6,2, 9,10 ],
	     ]
	     );
}

                           shape ( 20, 2,  5, 0.2);
translate( [ 5, 0, 0])  shape ( 20, 2,  5, 0.2);
translate( [ 10 , 0, 0])  shape ( 20, 2,  5, 0.2);